The figures are very, very nice. I always recommend the study of anatomy to re-enforce your knowledge of muscle and bone structure. Make drawings of the information you get from your study. Also, work on hands. Once you understand their structure, drawing hands are easy. Start with stick figure fingers. Each finger consists of 3 joints up to the knuckles. Get the dynamics and interaction of the figures down. Then you can expand on your finger drawing. Work on feet too - think triangles in almost all views.
A complex figure you are trying to draw can also use a stick figure to start with. I start with the head & shoulders. The relationships of the rest figure can be made.
Most important to improve your work: Practice makes better. Consequently, practice, practice, then practice more.